A pan‐cancer analysis indicated that TNFRSF9+ Treg (TNF Receptor Superfamily Member 9, also known as 4‐1BB and CD137) cells are widely present in various types of tumor tissues and exert strong immunosuppressive effects.[10] The transcription factor TCF‐1 (encoded by TCF7) plays a crucial role in the development of Treg cells, but in CRC, TCF‐1‐deficient Treg cells exhibit stronger immunosuppressive effects than WT Treg cells.[11] These studies suggest that further elucidating the impact of cytokines on Treg phenotypes and functions is highly important. Here, TNFRSF9 is linked to cancer.